ROCKVILLE — — What is probably Richard Lapointe’s last chance to prove that he was wrongly convicted of raping and killing an 88-year-old woman and then setting her apartment on fire more than 23 years ago began Monday in a Rockville courtroom.

Lapointe, 64, of Manchester, was convicted in 1992 of capital felony, felony murder, arson murder, murder and a host of other charges, and sentenced to life in prison without the possibility of release.

A group of supporters has worked to get a judge to consider evidence that they believe raises enough questions about his conviction to win him a new trial.

Superior Court Judge John J. Nazzaro began hearing that evidence Monday. The first witness was Michael Ludlow, a retired Manchester police detective who led the investigation into the killing of Bernice Martin.

Martin, the grandmother of Lapointe’s wife, was raped and strangled in her apartment on North Main Street in Manchester the evening of March 8, 1987. Ludlow took notes during the investigation, and one notation caught the eye of Lapointe’s attorneys — that the possible burn time of the fire was 30 to 40 minutes before Lapointe called 911 at 8:27 p.m.

Lapointe’s lawyer, Paul Casteleiro, contends that notation depicts the window of time in which the fire was set, and that Lapointe can be accounted for during that time, giving him an alibi.

Ludlow, who now works as a police officer at the University of Connecticut, testified that the note was not the estimated burn time, and that he lacked the expertise to make such an estimate. At a previous hearing in 2007, Ludlow testified that one of two fire investigators told him that span of time, but on Monday he said he could not recall who told him.

Further, he said, he was trying to get a sense of the minimum time the fire was burning so that he could develop a time line of the crime. “That’s ballpark,” he said. “It could have been 15 minutes to two hours. It’s not an exact science.”

Lapointe sat passively in the courtroom during the testimony. He looked to his supporters and others in the courtroom and nodded to them. At other times he worked on one of several word puzzle books.

Lapointe’s supporters say that he was coerced into signing a confession obtained from him by Manchester detectives during a 9½-hour interrogation in 1989. In it, Lapointe said that he had strangled Martin with his hands, even though police had found her body bound and choked with her own clothing.

Defense lawyers have argued that Lapointe did not know what he was doing during the questioning, because he made three confessions, each one contradicting the others and, in some cases, contradicting the evidence. At the 1992 trial, the jury deliberated for less than two hours before finding Lapointe guilty of raping and killing Martin, and then setting her house on fire to conceal the crime.

For years, his supporters have questioned whether police focused on the right suspect, arguing that Lapointe, who has a diminished mental capacity, was physically and mentally unable to commit the crime.

Lapointe’s supporters and a lawyer from a national group that represents those it believes are wrongfully convicted have pushed for a new trial for Lapointe.

At a hearing for a new trial in July 2007, Casteleiro argued that Lapointe deserved a new trial on the grounds that his public defenders in 1989 did not provide him with adequate representation and that his lawyer, in a bid for a new trial in 2000, was ineffective.

Judge Stanley T. Fuger eventually ruled against Lapointe before the hearing concluded.

In a ruling last year, the Appellate Court disagreed with Fuger, saying that Lapointe’s trial lawyers were ineffective, in that certain exculpatory evidence wasn’t presented.